Physical Vapor Deposition (PVD) is a plasma process that is commonly used in the manufacturing of many products, such as semiconductors, flat panel displays, and optical devices. Physical vapor deposition causes ions in a plasma to dislodge or sputter material from a target. The dislodged or sputtered target material is then deposited on a surface of a workpiece to form a thin film.
Independently controlling the uniformity of the sputtered film and the density of the plasma generated during PVD becomes more difficult as the size of the workpiece increases. In magnetron sputtering, large targets are typically required to sputter coat large workpieces. However, processing large workpieces can result in problems, such as poor target utilization, target cooling problems, and non-uniform coating of the workpieces.
Complex rotating magnet configurations have been used to improve plasma uniformity and to prevent non-uniform erosion of the target. In some systems, workpieces are moved relative to the plasma in order to increase the uniformity of the sputtered film. However, moving the magnets and/or the workpieces can result in a lower deposition rate. In other systems, the power applied to the target is increased to increase the deposition rate. However, increasing the power applied to the target can result in undesirable target heating. Compensating for temperature increases associated with increasing the power applied to the target by cooling the target in the deposition system increases the cost and complexity of the deposition system.